A COVID-19 variant identified last week as a “variant of interest” by the World Health Organization has not yet been reported in Pennsylvania, the state Department of Health said Wednesday.
According to data from the Centers for Disease Control and Prevention, the mu variant — first identified in Colombia and known by scientists as B.1.621 — has not been reported in Pennsylvania despite reports from some media outlets that the strain has appeared in every state except Nebraska.
The variant, which the CDC says makes up just 0.1% of U.S. cases in the week ending Sept. 4, was identified as a variant of interest by the WHO on Aug. 30 because of preliminary evidence showing that it may be able to evade antibodies. But health officials say that data is incomplete, and it is unlikely to topple the very contagious delta, which makes up almost 99% of cases in the country.
To determine prevalence of common variants, a Pennsylvania DOH spokesperson said the department sequences COVID-19 specimens and sends samples to the CDC. As of Sept. 7, there were 1,337 sequences collected by the CDC over a four-week period of time, showing the highly contagious delta variant remains the most prevalent in the commonwealth at 97.9% of those samples.
The alpha variant, first identified in the U.K. and known as B.1.1.7, made up 0.6% of sequences, while the gamma variant first found in Brazil accounted for 0.4% of the samples.
Both of those have been identified as variants of concern by the WHO, but the contagiousness of the delta variant has allowed it to remain the dominant strain in the U.S since the early summer. The remainder of the samples sequenced by the CDC came from other variants of the virus.
Like any virus, COVID-19 has been mutating since it first jumped into humans, said Dr. Amesh Adalja, a Pittsburgh-based infectious disease physician. But most variants don’t have much consequence, and only a few of the mutations end up causing serious concern, such as delta’s properties that allow it to be more than two times as contagious as prior variants.
Mu doesn’t seem to be a major threat to the U.S., Dr. Adalja said. “It doesn’t appear to be a dominant variant. It doesn’t seem to be able to get a toehold anywhere near the delta variant did, just because the delta variant is so fit.”
Unvaccinated people remain at greatest risk of becoming infected with and transmitting the virus. Infections in fully vaccinated people, while rare, are far less likely to lead to serious illness. And the CDC says vaccinated people who experience breakthrough infections from delta appear to spread the virus for a shorter time compared to those who are unvaccinated.
The CDC has not yet labeled mu a variant of concern, but the properties that have made mu a variant of interest to the WHO, such as its apparent ability to skirt past some antibodies provided by vaccines, need to be looked at more closely, Dr. Adalja said.
“I think we need to learn a lot more about it, because oftentimes when you see things like decreased vaccine neutralization in a laboratory study, that doesn’t necessarily correlate with what happens in the real world,” he said, adding that it’s unlikely any variant will be able to erase all the protections that vaccines provide that allow most people to avoid becoming very sick.
Other variants of interest marked by the WHO include eta, iota, kappa and lambda, all of which were first identified in the later months of 2020. Now, none of those variants is represented in current CDC samples. Although the iota was spreading in New York in early 2021, its prevalence took a sharp drive in July as delta became more widespread.
Right now, Dr. Adalja said the overall message continues to be that this is another reason to get a COVID-19 shot. “Vaccines will protect you against these variants when it comes to what matters, which is serious disease and hospitalization.”
Mick Stinelli: mstinelli@post-gazette.com; 412-263-1869; and on Twitter @MickStinelli
First Published: September 8, 2021, 5:00 p.m.